I’ve ran a few different gravel tires over the last year. Here’s my experience:
bontrager gr1 40mm: grippy but surprisingly slow, I really like bontrager mtb tires, but these are so slow. I’d say grippier and slower than you’d expect looking at their tread pattern.
continental terra speed 40mm: they seem to roll really fast so far, and fairly light with sidewall protection. actually measure 38mm on a 19mm WTB rim. I have less than 100 miles on them.
gravel king+ 35mm: my new go to tire for smooth gravel and rough roads. they roll fast and no flats yet.
vittoria terreno mix 40mm: mostly used for CX, but they roll surprisingly fast on gravel. sort of a strange tire but I like them. Probably won’t run on gravel now that I have terra speed and GK+. Maybe in muddy gravel conditions.
vittoria terreno dry: still in packaging, going to put them on my girlfriend’s new domane soon.
surly knard 41mm 120tpi: my first gravel tire, a good all arounder for putting miles on.